1. Field of the Invention
This invention relates to a valve for flow control and, more particularly, to a valve having a flow path offering low resistance against flow and including an improved plug.
2. Description of the Prior Art
There exist valves of the type wherein the flow therethrough is controlled by a cylindrical plug having a semi-spherical valve head which is driven back and forth at right angles with respect to a Venturi tube type inner flow path. Such a valve has an inherent substantial shortcoming in that there occurs an inversion phenomenon in its flow characteristic during its opening and closing operations, particularly in the valve opening range immediately before the full opening. This unstable characteristic of the valve seriously degrades its reliability when using it as a control valve.